CODEWITHSUNDEEP
node.jsdocker
HelloWorld
HelloWorld

Reputation: 3739

How do I measure docker memory usage including host os?

I'm running the following docker command:

docker run node -e "setTimeout(() => console.log('hello world'), 10000)"

Now, docker stats gives me:

CONTAINER ID        NAME                CPU %               MEM USAGE / LIMIT     MEM %               NET I/O             BLOCK I/O           PIDS
54b80bd39f0a        magical_babbage     0.00%               6.688MiB / 15.41GiB   0.04%               3.33kB / 0B         0B / 0B             7

Telling me that it's only using 6.88MiB.

Does docker not include the memory needed to run the host OS?

Upvotes: 3

Views: 3218

Answers (1)

erik404
erik404

Reputation: 615

Docker containers are run by a single operating system kernel which means that it does not run the OS as it would in a VM or on the host. Where an OS installed on a VM or host is booted as a "live" OS, Docker waits till it needs to use a specific process, this is achieved because Docker is loaded as a daemon process (dockerd) on the host machine.

The Alpine Linux image which is a widely used distro for Docker containers is only around 2.5MB in size. So you can understand that the memory usage for a Docker container using Alpine is very low.

The output you see with docker stats is the complete memory used by your container.

See Dockers metrics documentation for extensive information.

https://docs.docker.com/config/containers/runmetrics/

Upvotes: 6

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